Absorbent articles for personal hygiene of the type indicated above are designed to absorb and contain body exudates, in particular large quantity of urine. The absorbent articles usually comprise several layers having different functions, for example a topsheet, a backsheet and in between an absorbent core, among other layers. The function of the absorbent core is to absorb and retain the exudates for a prolonged amount of time, for example, overnight for a diaper, minimize re-wet to keep the wearer dry and avoid soiling of clothes or bed sheets.
The majority of currently marketed absorbent articles comprise as absorbent material a blend of comminuted wood pulp fibers with superabsorbent polymers (SAP) in particulate form also called absorbent gelling materials (AGM), see for example U.S. Pat. No. 5,151,092 (Buell). Absorbent cores with slits or grooves have also been proposed, typically to increase the fluid acquisition properties of the core or to act as a folding guide.
WO2012/170778 (Rosati et al., see also WO2012/170779, WO2012/170781 and WO2012/170808) discloses absorbent structures that comprise superabsorbent polymer particles, optionally a cellulosic material, and at least a pair of substantially longitudinally extending channels. The core wrap can be adhesively bonded through the channels to form a channel bond. The channel bonds may be permanent, so that their integrity is at least partially maintained both in dry and wet state. As the absorbent structure absorbs liquid and swells, the absorbent structure takes a three-dimensional shape with the channels becoming visible. The channels are indicated to provide improved fit and/or better liquid acquisition/transportation, and/or improved performance throughout the use of the absorbent structure.
The properties of superabsorbent polymer particles have been characterized in various ways. The absorbent capacity (CRC) in grams of liquid per gram of superabsorbent particles has been used, as well as the absorption speed as measured by the Free Swell Rate (FSR) and their permeability as measured by the Urine Permeability Measurement (UPM) test.
It has now been found that the creation of channels by bonding the core wrap may affect the performance of the absorbent core comprising absorbent material such as superabsorbent polymer particles and fibrous absorbent material.
Therefore, there is a need for absorbent core having superabsorbent polymers particles that have special performance in order to overcome the potentially negative consequences of the creation of channels.